1. Field of the Invention
This invention relates to lubricating oil compositions and to lubricant additives. More particularly, overbased aminoguanidine sulfonate can be used as an additive to impart beneficial properties such as acid neutralization to lubricants.
2. Description of Prior Art
During the combustion of hydrocarbon fuels, acidic byproducts, and sludge are formed. These acidic materials and sludge are carried down into the lubricant present in internal combustion engines. The acidic materials and sludge, if left untreated, would cause severe deterioration of the lubricating properties of the lubricant. Additives are commonly added to lubricant to add properties needed for lubrication of modern engines. Modern lubricants must be able to suspend sludge and neutralize acidic materials produced by combustion.
Materials disclosed in the prior art which impart acid neutralizing properties are commonly formed by overbasing a hydrocarbon sulfonic acid with metal bases such as magnesium oxide, barium oxide, and calcium oxide. As the lubricating oil which contains the metal sulfonates is consumed, the metal forms ashy deposits and residue. This ashy residue causes problems. The ash can poison catalytic converters, interfere with normal combustion of fuel, and reduce the effectiveness of other additives in the lubricating oil. It is difficult and time consuming to produce metal overbased additives.
U.S. Pat. No. 2,823,182 discloses a normally liquid oleaginous compound, preferably a hydrocarbon oil, and from about 0.5% to about 70%, and preferably from about 1% to about 20%, of a guanidine sulfonate. The guanidine sulfonate can be the guanidine or alkyl guanidine salt of hydrocarbon oil sulfonic acids obtained in the treatment of hydrocarbon oils with strong sulfuric acid or of alkanesulfonic acids or of arylsulfonic acids, alkyl aryl sulfonic acids, and mixtures thereof. The sulfonic acids can be preferentially oil-soluble sulfonic acids or preferentially water-soluble sulfonic acids. However, when the guanidine salts of preferentially water-soluble sulfonic acids, i.e., low molecular weight, are employed, they are used in combination with salts of preferentially oil-soluble sulfonic acids.
U.S. Pat. No. 2,660,562 discloses improved ashless lubricant compositions comprising mineral oils incorporated with a guanidine salt of an organic sulfonic acid selected from the group consisting of synthetic guanidine alkyl aryl sulfonates and guanidine petroleum sulfonates, and containing from 0.1 to 60 weight percent of the guanidine salt.
U.S. Pat. No. 2,702,819 discloses synthetic guanidine alkyl hydrocarbonaryl sulfonates containing a total number of at least 10 carbon atoms in the alkyl groups. Many guanidine sulfonates are very insoluble compounds, unsuitable as lubricant additives.
Thus it is an object of the invention to produce an ashless additive composition. Another object of the invention is to produce an overbased additive which contains no metal salts. Still another object of the invention is to solubilize in lubricants large amounts of ashless basic materials. Another object of the invention is to produce an additive which does not poison catalytic converters, deposit metal ash in combustion chambers, but has acid neutralization, antirust, anticorrosive, dispersant, and detergent properties in lubricants.